By Dennis Harvey

IT'S ALMOST A given in "serious" science fiction movies – as opposed to those primarily concerned with lightsaber fights and tentacled carnivores – that the future will not be bright. Totalitarian dystopia and postapocalyptic chaos invariably rule. The meek haven't inherited the earth, the strong have gotten really pushy, and a glass of water is likely to cost you your life or liberty or first-born daughter. Indeed, you could argue that even the cheapest, silliest '80s Mad Max clones possess an eco-political consciousness missing from movies in other genres. After all, they operate from the assumption that our ever accelerating paths of warfare and wasteful mass consumption will one day just fuck the whole thing up for everybody.

Even more sober-sided treatments of this theme flourished in the late '60s and early '70s, when films could reflect the radical politics of their era, including its newfound sense of ecological emergency. Commercially marginal films like A Boy and His Dog and THX 1138 and populist efforts such as Soylent Green and the original Planet of the Apes offered grim predictions unleavened by much hope or warmth. The logical way around such comforting impulses was to hinge matters on an us-versus-them romance, making love itself a fool's game amid violent anarchy – if not an outright crime against a fascist future state.

Code 46 is prolific British director Michael Winterbottom's first science fiction movie. It sandwiches all the above – illicit love and procreation, a civilization that is both Big Brother-ized and gonesville – into a story nonetheless intimate, casual, even a tad slight.

In the film's unspecified near future, globalization seems complete. Speech is a Spanglish polyglot filigreed by entry-level phrases from many tongues. Major cities are interchangeable knots of highway, corporate headquarters, and living cubicles. Haves and have-nots are now kept apart by armed checkpoints. The latter live in a less bloodthirsty Mad Max desert landscape of vanished resources and barter economics, while the former continue a material-clutter lifestyle within strictly regulated behaviorial confines. One big no-no is conception between parents who share more than 25 percent "genetic identity" – so many people have been cloned from such a limited pool of healthy DNA that complete strangers might commit "incest." Screening, abortions, and severe punishment of intentional transgressions are the law.

Insurance investigator William (Tim Robbins) flies from Seattle to Singapore, where there's been a security breach: someone is forging "papelles" (documents that allow travel beyond one's home city) for black market sale. It can only be an inside job in the Sphinx passport plant. As William endeavors to solve Sphinx's riddle, an "empathy virus" allows him to glean people's thoughts while engaging them in trivial conversation.

Thus equipped, he interviews employees to find the culprit. Yet he steers suspicion away from line worker Maria (Samantha Morton) because, gosh, it's love – or at least strong like – at first sight. He's there on a 24-hour pass, and their necessarily curtailed affair has immediate repercussions. Sternly sent back to Shanghai, William finds things have taken a peculiar turn for Maria and must decide whether to leap off the grid into a chaotic, papelle-deprived life outside with her.

Code 46's screenplay is by the director's frequent collaborator Frank Cottrell Boyce, but it's well-known that Winterbottom encourages improvisation, and the film sports a sense of real-world character detail seldom found in science fiction flicks. Then again, most sci-fi movies value spectacle, action, and exotica a great deal more than this one, which will come across as a snooze to your average Matrix fan.

In the film's unusually believable future, change is for the most part modest. The rich got much richer and the poor even poorer, as expected. Mother Earth is now truly gagging on our bad habits; urban life for the respectable citizen looks more like a Tokyo work drone's existence. The film's chief point of interest is also its least novel: gray-flannel-suit type William and urbanized Earth First!-cum-Burning Man grrrl Maria make for a pairing that's improbable even to themselves, yet they're palpably drawn together by an irresistible force.

Winterbottom's crowded oeuvre contains 13 features from the past decade, and it looks almost random at first glance, encompassing torn-from-headlines horror (Welcome to Sarajevo, In This World), costume epic (The Claim, Jude), the gospel according to NME (24 Hour Party People and the upcoming Nine Songs), and a venture into serial murder (Butterfly Kiss). Perhaps this restlessness explains why he's made so many good, or at least intriguing, films so far and yet no great ones. One thing uniting them all, however, is the gravitational pull of star-crossed lovers whose personalities and circumstances are immaculately felt, whatever melodrama may come to bear on them.

Morton and Robbins are fine actors who've often done their best work in movies few bother to see. It's safe to say that Code 46 will rank among the latter; nobody goes to a science fiction movie for the acting. But there's so much individual nuance in and sympathetic rapport between their performances that the film needn't be about much beyond love, plus all the stuff (prior commitments, geography, legislation) that gets in its way. Code 46 is uneven, maybe too low-key for its own good. But it's also sweet, sad, and sexy to degrees that make you realize most romantic on-screen "chemistry" is routine and phony in comparison.

'Code 46' opens Fri/13 at the Lumiere Theatre, 1572 California, S.F. See Movie Clock, in Film listings, for show times.